ProtologueCat. horti camald., ed. 2: 6, 20 (1832).FamilyMyrtaceae
Chromosome number2n = 22SynonymsEucalyptus rostrata Schltdl. (1847).Vernacular namesRiver red gum, Murray red gum, red gum (En). Eucalyptus rouge, gommier rouge (Fr). Eucalipto vermelho (Po). Mkaratusi (Sw).Origin and geographic distributionThe natural distribution of Eucalyptus camaldulensis covers most of the Australian mainland, ranging from the tropical Northern Territory to cool, temperate Victoria. It is planted in many tropical and subtropical countries, probably being the world’s most widely planted tree in arid and semi-arid lands, and it has become naturalized in many areas. It has been planted in Africa since 1900 and it is now very widely grown in tropical Africa, where it is probably the most common tree in woodlots, shelterbelts and fuelwood plots, but less important in large-scale plantations.UsesThe wood of river red gum is used mainly for firewood, charcoal, poles, posts, tools and paper pulp. Other uses include construction (especially bridges and wharves), flooring, ship building, railway sleepers, mine timber, furniture and packing cases. It is also used for veneer, plywood, turnery, hardboard, fibreboard and particle board.River red gum is often planted for shade, as windbreak, as an ornamental, for amenity purposes and as a source of nectar to produce high-quality honey. It is planted to rehabilitate saline land, being able to utilize saline groundwater. In Somalia it is planted on sand dunes and along roads. The leaves may be eaten by livestock. The bole has potential as a substrate for shiitake mushroom (Lentinus edodes) cultivation, and yields a gum (red kino) which can be used as a dye.An essential oil, traded as eucalyptus oil, is obtained from the leaves of mainly tropical provenances. It is used for medicinal purposes, especially as a cough remedy and expectorant, but it also has febrifuge, tonic, astringent, antiseptic, haemostatic and vermifugal properties.In Senegal a leaf decoction sweetened with sugar is used to treat stomach-ache and dysmenorrhoea. In Sudan fresh leaves are applied against rheumatism, and the smoke of burnt leaves is inhaled for the treatment of respiratory problems. The gum is used medicinally to treat diarrhoea and pharyngeal inflammations, and as an astringent. In Nigeria chewing sticks are obtained from the tree. The smoke of burnt leaves serves to repel insects.Production and international tradeIn addition to extensive, but largely unrecorded, small-scale plantings of Eucalyptus camaldulensis worldwide for fuelwood, shade and shelter, over 500,000 ha of plantations had been established by the mid-1970s, mainly in the Mediterranean region using provenances from southern Australia. Later better adapted provenances from northern Australia have been planted in tropical areas. In 1995 it was estimated that worldwide Eucalyptus plantations amounted to 14.6 million ha, of which 1.8 million ha in Africa, much of this is in South Africa. The proportion of Eucalyptus camaldulensis in the plantations is not known. Wood production for domestic consumption is substantial. Wood chips for paper production are exported by several African countries, but statistics for domestic consumption and exports are lacking.PropertiesThe heartwood has a red colour, turning red-brown upon exposure, and is clearly demarcated from the paler, 5–7.5 cm wide sapwood. The grain is interlocked, straight or wavy, often producing an attractive figure, texture is moderately coarse. The wood of plantation-grown river red gum often has unfavourable characteristics such as growth stresses, shrinkage on drying, collapse, spiral grain and starch in the sapwood.The wood is moderately heavy, with a density of 680–980 kg/m³ at 12% moisture content, with samples from natural forest having the higher densities. The density of plantation-grown river red gum wood varies with age, provenance and planting site, but does not appear to be closely correlated with rate of growth. Charcoal and pulp yield are positively correlated with density. Provenances from tropical northern Queensland (e.g. ‘Petford’) produce wood with the highest density and thus the highest yields of charcoal and pulp. Mature material can be air dried with little degrade. For best results, drying should be done slowly. The rates of shrinkage from green to oven dry are 5.6% radial and 8.6% tangential. The wood is not stable in service.The wood is hard and strong. At 12% moisture content the modulus of rupture is 101–192 N/mm², modulus of elasticity 10,500–14,700 N/mm², compression parallel to grain 49–72 N/mm², shear 5–15 N/mm², cleavage 16–33 N/mm, Janka side hardness 9380–9635 N, Janka end hardness 9650–10,415 N and Chalais-Meudon side hardness 2.9–6.1.The wood is easy to saw despite its high density, but splitting may occur due to the release of growth stresses. It is difficult to work and should be pre-bored before nailing, but gluing properties are good and the wood polishes well. It is suitable for steam-bending.The wood is considered durable, but the durability of wood from plantation-grown trees is less than that of trees in natural stands in Australia. The heartwood is resistant to termites; the sapwood is susceptible to attack by Lyctus borers. Preservation is necessary if the timber is to be in contact with the ground; the heartwood is extremely resistant, the sapwood is permeable to preservatives.The energy value of the wood is 17,700–21,000 kJ/kg. The chemical composition of the oven-dry wood is: cellulose 41–50%, pentosans 14–19%, lignin 18–34%, ash 0.4–0.9%. The solubility in hot water is 2–10%, in alcohol-benzene 1–7% and in 1% NaOH 17–21%. Fibre cells in wood from Sudan are on average 9 mm long, with a diameter of 15 μm and a cell wall thickness of 6 μm. Pulping of Sudanese material with various chemical processes gave yields of 44–55% of pulp with good mechanical properties.The leaves of river red gum yield up to 3% of an essential oil traded as eucalyptus oil. The chemical composition is variable and is determined mainly by the provenance and to a lesser extent by the environment or the season of harvesting. Differences in the method of extraction also cause differences in composition; hydrodistillation especially causes decomposition of several components. Three main types of eucalyptus oil can be recognized. Many tropical provenances (e.g. ‘Petford’) yield an oil rich in 1,8-cineole (35–93%) and p-cymene (2–20%) and are a potential source of medicinal-grade eucalyptus oil; oil from subtropical origins is often characterized by cryptone (about 15%) and p-cymene (20–35%) or by spathulenol (15–20%), p-cymene (20–30%) and cryptone (4–7%). Other characteristic components include aromadendrene and allo-aromadendrene, α-terpineol and terpinen-4-ol.The essential oil has antibacterial, antifungal and antioxidant activity. It has also repellent activity against Aedes aegypti and Culex pipens mosquitos. Compounds with strong mosquito repellent activity isolated from the oil include eucalamol and 4-isopropylbenzyl alcohol. The essential oil as well as powdered leaves have shown insecticidal activity against various storage pests. Crude leaf extracts had antifeedant activity against cotton bollworm (Helicoverpa armigera) larvae. The essential oil and water and ethanol extracts of the leaves have shown molluscicidal activity. Several triterpenoid constituents have been isolated from the leaves, e.g. camaldulin, ursolic acid lactone acetate, ursolic acid lactone, betulinic acid, oleanolic acid, amirinic acid and β-sitosterol 3-O-β-D-glucopyranoside. The first 3 compounds have been tested for spasmolytic activity and were found to possess calcium antagonist activity. Crude leaf extracts have shown in-vivo anti-ulcer activity in rats, and ethanol extracts of the leaf have shown in-vivo antinociceptive effects in mice.River red gum is a host tree of Cryptococcus neoformans, a biotrophic smut-like fungus causing cryptococcosis, a serious disease in humans usually resulting in meningitis or pneumonia. This infection is locally common in Australia, and has spread elsewhere, where it is often found in AIDS patients.DescriptionEvergreen, medium-sized to sometimes large tree, commonly up to 20 m tall, occasionally reaching 50 m; bole branchless for up to 20 m, up to 100(–200) cm in diameter; bark surface smooth, white, grey, yellow-green, grey-green or pinkish-grey, shedding in strips or irregular flakes. Leaves alternate, pendulous, simple and entire; stipules absent; petiole rounded or channelled, 1–1.5(–3) cm long; blade narrowly lanceolate to lanceolate, often sickle-shaped, 8–30 cm × 0.5–2(–2.5) cm, acute at apex, hard and stiff, glabrous, pinnately veined, aromatic when crushed. Inflorescence an axillary, simple, umbel-like, condensed and reduced dichasium, (5–)7–11-flowered; peduncle slender, rounded or quadrangular, 5–15(–25) mm long. Flowers bisexual, regular, creamy to whitish; pedicel slender, 5–12(–14) mm long; flower buds globular beaked or ovoid-conical, divided into a hemispherical hypanthium (lower part) 2–3 mm × 3–6 mm, and a beaked to conical operculum (upper part) 4–6 mm long and shed at anthesis; stamens numerous; ovary inferior, 3–5-celled, style awl-shaped. Fruit a thin-walled, hemispherical or ovoid capsule 3–10 mm × 4–10 mm enclosed in a woody hypanthium, opening with 3–5 strongly exserted valves, reddish brown to brown, many-seeded. Seeds minute, smooth, yellow-brown. Seedling with epigeal germination; cotyledons 2-lobed; first 4–6 pairs of leaves decussately opposite, subsequent leaves alternate; leaves ovate to broadly lanceolate, 13–26 cm × 4.5–8 cm.Other botanical informationEucalyptus comprises about 800 species, endemic to Australia, except for about 10 species in the eastern part of South-East Asia. Many Eucalyptus species are cultivated outside their natural distribution area, in tropical, subtropical and temperate regions, because of their rapid growth and adaptation to a wide range of ecological conditions. In Africa Eucalyptus globulus Labill. has long been the most important Eucalyptus species, but its importance has declined, although it is still important in cooler climates. Nowadays the main commercial species in Africa are Eucalyptus grandis W.Hill ex Maiden in more fertile locations, Eucalyptus camaldulensis in drier regions, and Eucalyptus robusta Sm. in tropical regions.Eucalyptus is divided into several subgenera (7–10, depending on the author), which are subdivided into many sections and series. The results of phylogenetic studies within Eucalyptus suggest that the genus is polyphyletic, hence not of a single evolutionary origin, and consequently it has been proposed to divide the genus into several distinct genera. This has not yet been done, mainly because of the nomenclatural whirlpool this would bring about. Eucalyptus species hybridize easily, which adds to the taxonomic complexity.There is considerable morphological variation within Eucalyptus camaldulensis, which is not surprising given its wide geographic distribution. Six varieties have been described, but this division has been largely ignored because of difficulties in identification. The northern and southern provenances are sometimes accommodated in two varieties: var. camaldulensis and var. obtusa Blakely, respectively. Var. camaldulensis has beaked opercula, whereas var. obtusa has obtuse or rounded ones. However, the variation in this character seems to change gradually with location.Eucalyptus camaldulensis is closely related to Eucalyptus tereticornis Sm. The latter can be distinguished by its taller and more steeply branched habit, its acutely conical operculum and black, rough-coated seeds. Where both species grow naturally, as in eastern Victoria and Queensland, hybridization and subsequent introgression occurs. Several populations in far northern Queensland, previously identified as Eucalyptus tereticornis, show several characteristics of Eucalyptus camaldulensis and are now considered a separate subspecies of the latter (subsp. simulata Brooker & Kleinig). Among them are the fast-growing provenances ‘Laura River’, ‘Palmer River’ and ‘Walsh River’ that are widely planted in tropical regions. Natural hybrids between Eucalyptus camaldulensis and Eucalyptus alba Reinw. ex Blume are also reported, while hybridization with Eucalyptus grandis occurs in plantations.AnatomyWood-anatomical description (IAWA hardwood codes):Growth rings: 2: growth ring boundaries indistinct or absent. Vessels: 5: wood diffuse-porous; (7: vessels in diagonal and/or radial pattern); 9: vessels exclusively solitary (90% or more); 13: simple perforation plates; 22: intervessel pits alternate; 26: intervessel pits medium (7–10 μm); (27: intervessel pits large (≥ 10 μm)); 29: vestured pits; 31: vessel-ray pits with much reduced borders to apparently simple: pits rounded or angular; (32: vessel-ray pits with much reduced borders to apparently simple: pits horizontal (scalariform, gash-like) to vertical (palisade)); 42: mean tangential diameter of vessel lumina 100–200 μm; (45: vessels of two distinct diameter classes, wood not ring-porous); 47: 5–20 vessels per square millimetre; (56: tyloses common). Tracheids and fibres: 60: vascular/vasicentric tracheids present; 62: fibres with distinctly bordered pits; 63: fibre pits common in both radial and tangential walls; 66: non-septate fibres present; 69: fibres thin- to thick-walled. Axial parenchyma: 76: axial parenchyma diffuse; (77: axial parenchyma diffuse-in-aggregates); 78: axial parenchyma scanty paratracheal; (79: axial parenchyma vasicentric); 84: axial parenchyma unilateral paratracheal; 92: four (3–4) cells per parenchyma strand; (93: eight (5–8) cells per parenchyma strand). Rays: 97: ray width 1–3 cells; 104: all ray cells procumbent; (106: body ray cells procumbent with one row of upright and/or square marginal cells); 116: ≥ 12 rays per mm.(D. Louppe, P. Détienne & E.A. Wheeler)Growth and developmentSeed germination rate of river red gum is generally high and can reach almost 100%. Growth rates vary greatly between provenances and are heavily site-dependent. Although annual seedling growth rates of up to 4(–7) m in height and up to 4(–6) cm in diameter have been recorded for well-adapted provenances on favourable sites in the tropics, in drier areas in Zimbabwe young trees from different provenances were on average slightly over 6 m tall 5 years after planting. The tree develops a strong taproot and the lateral roots can attain lengths 2.5 times the height of the tree, making it particularly effective for erosion control. In tropical regions, some provenances may flower almost throughout the year. Pollination is mainly by insects but also by birds and small mammals. Seeds ripen about 6 months after pollination. River red gum may start flowering when 1.5–2 years old. On favourable sites in the tropics, the period from planting to production of the first seed crop may be as short as 3 years. Eucalypts do not develop resting buds and grow whenever conditions are favourable.EcologyUnder natural conditions, river red gum occurs typically along watercourses and on floodplains, usually in open forest and woodland, up to 700 m altitude. Planted trees grow under a wide range of climatic conditions, from temperate to hot and from humid to arid. Annual rainfall in natural stands varies from 250–2500 mm, but planted trees can survive in areas with as little as 150 mm annually. Survival in arid regions depends on the presence of a high water table or seasonal flooding. In Africa best growth is observed in areas with an average annual rainfall of 700–1200 mm. The length of the dry season may vary from 0–8 months. Mean annual temperatures range from 13–28°C. Mean minimum temperature of the coldest month ranges from 3–22°C, mean maximum temperature of the hottest month from 21–40°C. In general, river red gum tolerates up to 20 frosts per year, but does not tolerate temperatures below –10°C. In tropical Africa it is grown from sea-level up to 2800 m altitude.River red gum occurs on a variety of soils, commonly on sandy and silty alluvial soils, but in southern Australia occasionally on heavy clays. It is found along the borders of salt lakes and adapted cultivars are grown on saline waterlogged soils in degraded irrigation schemes. River red gum is not adapted to calcareous soils, except for a few populations in southern and western Australia growing on shallow soils over limestone. Provenances may differ considerably in frost, fire and salt tolerance.Propagation and plantingRiver red gum is usually propagated by seed. The 1000-seed weight is 0.3–5 g. In general, 1 kg of seed is sufficient to provide plants for 100 ha at a spacing of 3 m × 2 m and the typical seedling recovery rate of 25%. Seed is best stored dry (5–8% moisture content) in airtight containers at 3–5°C. Viability will be maintained for several years and is still about 30% after being stored for 7 years. No pre-sowing treatment is required. The optimum temperature for germination is 32°C, but a wide range is tolerated. The fine yellow-brown seed is sown under shade in a well-drained and sterilized medium and covered very sparingly with sand. After 4 days, seed has germinated and shade should be reduced. When 2 pairs of leaves have developed, seedlings are pricked out into containers such as polythene bags filled with a sterilized potting mix. A polythene bag size of 15 cm × 5 cm proved most economic in Nigeria. Shading is needed for the first week after transplanting, thereafter plants should be fully exposed. Direct sowing in polythene bags or in open nursery beds for the production of bare-rooted planting stock is also practised. Plants can be planted out after 3–5 months, occasionally after 6 weeks, when they are 20–30 cm tall. Excessive watering and shade often result in damping-off or in seedlings becoming too tall and weak for easy transplanting. In Ethiopia farmers sometimes spread branches with mature fruits on the planting site, and when the fruits have opened and the seeds have been dispersed, the soil is kept moist to ensure germination. When the plants have established, the branches are removed, and later the stand is thinned to a suitable spacing.River red gum is suited to mass vegetative propagation. Cuttings from juvenile shoots (i.e. below the 10th node) root readily in about 30% of genotypes. A major reforestation project in Morocco is based entirely on cuttings of river red gum. Propagation by cuttings is an integral component of breeding programmes. Elite trees are selected in young plantations (5 years old) and felled or girdled to promote coppicing. Coppice shoots of about 1 m long are collected and divided into pencil-sized cuttings with 2 leaf pairs. Half of the leaf blade is then trimmed and the cuttings are dipped into a hormone preparation and planted in pots under mist and shade. Rooted cuttings are usually planted in nurseries to provide further shoots. Grafting is also possible and methods of in-vitro propagation have been developed.Spacing varies with the management system and depends on the end products required. For firewood, spacings as close as 2 m × 2 m are used; for pulpwood, a spacing of 3 m × 2 m is often used. Wider spacings of 4 m × 2 m, 5 m × 2 m or 4 m × 4 m are recommended when larger trees are the objective. In plantations, river red gum has a comparatively narrow crown which allows light to reach the forest floor. This is favourable for intercropping with food crops but also allows weed growth. Spacings of 5 m × 2 m or 4 m × 4 m are recommended for intercropping during the first 2–3 years. Application of 100 g of NP or NPK (3:2:1) fertilizer per tree at planting to assist establishment and early growth is common. Competition for water and nutrients can severely reduce yields of interplanted crops. River red gum is also recorded to have allelopathic effects on undergrowth and crops near the tree, probably due to the release of phenolic compounds from fallen leaves.ManagementFrequent weeding, up to 3 times per year, is necessary until the canopy closes 3–5 years after planting. Inadequate weed control may lead to complete failure of the plantation. Intercropping may facilitate weed control. Thinning to less than 700 stems/ha at 5 years provides posts, poles, fuelwood and pulpwood, leaving better trees for the production of, for example, sawn timber after 10 years.Crown dieback, resulting from boron deficiency, is prevalent in parts of Africa, Asia and South America during the dry season and must be corrected. A dosage of 10–20 g of borax per tree is recommended, depending on soil type.All fast-growing provenances tested coppice well. The rotation may be as short as 3–5 years for small-sized pulpwood, but is generally 8–10 years. In Israel a plantation has been maintained successfully for 5 successive 10-year coppice rotations, but in general 2–3 coppice rotations of 10–12 years are feasible. Reduction of the number of coppice shoots on a stool is an important, although time-consuming, management operation. In Nepal a single reduction at 3–6 months to one shoot per stump is recommended.Diseases and pestsIn the nursery, river red gum is susceptible to various fungi causing damping-off and leaf diseases. Proper hygiene and watering sparingly minimize damage. Insects (e.g. termites, locusts and aphids) and rodents may be troublesome. However, on suitable sites outside Australia, river red gum is relatively free of diseases and pests. Stem canker and leaf diseases proliferate where rainfall and humidity are much higher than in the natural habitat. In Ethiopia Eucalyptus camaldulensis suffers from a stem canker disease caused by Coniothyrium zuluense, characterized by the presence of necrotic lesions, cracking of stems, gum pockets in the wood, and malformation of stems. In the humid tropics, river red gum may be defoliated by fungi including Cylindrocladium spp. during the rainy season. The most susceptible provenances suffer mortality and general decline, but well-adapted provenances (e.g. ‘Katherine’) are little affected.In parts of Africa and Asia, termites attack seedlings and young trees and must be chemically controlled. In Africa the eucalyptus snout beetle (Gonipterus scutellatus), of Australian origin, feeds on young shoots but is controlled biologically; moribund or newly-felled trees may become infested with an Australian stem borer or the longicorn beetle (Phoracantha semipunctata).HarvestingRiver red gum is usually grown on a short rotation and clear-felled at an age that maximizes production for a particular end-use. The felling season affects coppice regeneration. Felling during the dry season delays sprouting and increases the risk of the stump drying out. Felling by saw to give a clean-cut short stump with minimum bark damage is best. In coppice systems, e.g. in Nepal, some stems are sometimes left uncut as standards. This practice is recommended to produce wood of a range of diameters suitable for various products. The leaves are sometimes left on the tree after felling to accelerate drying of the wood and to reduce borer attacks.YieldVery high productivity is possible under favourable conditions: a mean annual increment of 70 m³/ha of 4-year-old trees planted at 3 m × 2 m on a fertile site with high water availability has been recorded in Israel. However, such conditions are seldom met. In the drier tropics, yields of 2–10 m³/ha per year on a 10–20-year rotation are common, whereas in moister regions up to 30 m³/ha per year may be achieved on 7–20-year rotations. Coppice rotations give higher yields than the initial seedling rotation (e.g. 25–30 m³/ha per year versus 17–20 m³/ha per year in Turkey) and the length of the rotation may be adjusted accordingly.Near Ouagadougou (Burkina Faso) large plantations were a failure; after good initial growth during the first years the productivity fell down to about 1 m³/ha/year, whereas yields are much higher in small plantations. In northern Côte d’Ivoire 10-year-old trees of the best provenances produced 13–15 m³/ha per year. In irrigated plantations in Niger and Senegal yields of 20–35 m³/ha per year on a 30-month rotation have been recorded, whereas higher yields were achieved on temporary flooded soils in the Niger valley. In Niger very good growth was obtained with drainage water from irrigated areas, and in Sudan with domestic wastewater from cities.Handling after harvestEnd-splitting of roundwood may be reduced by felling during winter months. For sawn timber production in Pakistan, it is recommended to fell in October, convert immediately into 70 mm quarter-sawn planks, carefully stack in a well-ventilated room and then top load each stack in order to reduce defects.Genetic resourcesIt is often impossible to trace the origin of Eucalyptus camaldulensis seed used for plantations, so the extent of genetic variation available in various areas is uncertain. Systematic introduction of appropriate seedlots from native Australian stands is highly recommended to ensure that a wide genetic variation is used for selection and breeding. Many provenance tests have been conducted with the help of CTFT and Cirad in Sénégal, Burkina Faso, Côte d’Ivoire, Niger and Congo, and seed orchards have been established.In Australia, two groups of provenances are distinguished: a northern tropical group and a southern temperate group. The better-performing tropical provenances, such as ‘Petford’ and ‘Katherine’ are generally the most sought-after for breeding programmes in tropical Africa. The Australian Tree Seed Centre (ATSC) provides well-documented single-tree and bulk provenance collections of river red gum for breeding programmes.A genetic linkage map of Eucalyptus camaldulensis has been constructed based on RAPD (random amplified polymorphic DNA), RFLP (restriction fragment length polymorphism) and nuclear microsatellite markers. Genome sequencing is in progress.BreedingThe ideal commercial tree should have good vigour and resistance to diseases and pests, a straight single bole, drought tolerance, good coppicing ability, high pulp yield (light-coloured timber), thin branches and good self-pruning ability, and a thin bark.Although seed availability of climatically adapted northern Australian provenances has increased, supplies are still insufficient to meet demand. Consequently, a number of tropical countries support selection and breeding programmes, for instance Zimbabwe. Transgenic lines containing both a gene conferring tolerance of the herbicide glufosinate ammonium and a gene providing insecticidal properties, e.g. against chrysomelid beetle larvae have been developed.ProspectsRiver red gum is one of the best performing trees in the seasonally dry tropics for an impressive array of end-products. It is superior to other exotic trees for production of firewood, charcoal and wood for other purposes on infertile dry sites. It tolerates drought and high temperature and grows rapidly when water is available, tolerating periodic waterlogging and soil salinity and (to a certain extent) fire and frost. Its productivity and versatility can be enhanced by breeding programmes now under way in several tropical regions (but few in Africa). With careful selection of provenances, river red gum is expected to gain importance in tropical Africa.Major references• Bolza, E. & Keating, W.G., 1972. African timbers: the properties, uses and characteristics of 700 species. Division of Building Research, CSIRO, Melbourne, Australia. 710 pp. • Burkill, H.M., 1997. The useful plants of West Tropical Africa. 2nd Edition. Volume 4, Families M–R. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 969 pp. • Chippendale, G.M., 1988. Myrtaceae - Eucalyptus, Angophora. In: George, A.S. (Editor). Flora of Australia, Volume 19. Australian Government Publishing Service, Canberra, Australia. 540 pp. • Doran, J.C. & Wongkaew, W., 1997. Eucalyptus camaldulensis Dehnh. In: Faridah Hanum, I. & van der Maesen, L.J.G. (Editors). Plant Resources of South-East Asia No 11. Auxiliary plants. Backhuys Publishers, Leiden, Netherlands. pp. 132–137. • Eldridge, K., Davidson, J., Harwood, C. & van Wijk, G., 1993. Eucalypt domestication and breeding. Clarendon Press, Oxford, United Kingdom. xix + 288 pp. • Jacobs, M.R., 1981. Eucalypts for planting. 2nd Edition. FAO Forestry Series No 11. Food and Agriculture Organization of the United Nations, Rome, Italy. 677 pp. • Lamb, D., Johns, R.J., Keating, W.G., Ilic, J. & Jongkind, C.C.H., 1993. Eucalyptus L’Hér. In: Soerianegara, I. & Lemmens, R.H.M.J. (Editors). Plant Resources of South-East Asia No 5(1). Timber trees: Major commercial timbers. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 200–211. • Midgley, S.J., Eldridge, K.G. & Doran, J.C., 1989. Genetic resources of Eucalyptus camaldulensis. Commonwealth Forestry Review 68: 295–308. • Onyewotu, L.D.Z. & Stigter, C.J., 1995. Eucalyptus – its reputation and its roots. Millet and a eucalyptus shelterbelt in northern Nigeria. Agroforestry Today 7: 7–8. • Samate, A.D., Nacro, M., Menut, C., Lamaty, G. & Bessiere, J.M., 1998. Aromatic plants of tropical West Africa. 7. Chemical composition of the essential oils of two Eucalyptus species (Myrtaceae) from Burkina Faso: Eucalyptus alba Muell. and Eucalyptus camaldulensis Dehnhardt. Journal of Essential Oil Research 10(3): 321–324.Other references• Arbonnier, M., 2000. Arbres, arbustes et lianes des zones sèches d’Afrique de l’Ouest. CIRAD, MNHN, UICN. 541 pp. • Begum, S., Farhat, F., Sultana, I., Siddiqui, B.S., Shaheen, F. & Gilani, A.H., 2000. 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